AI Optical Communication Stocks Plummet... 7 Trillion Won in Market Cap Vanished in a Day

Ciena Corp. (CIEN) slid 8.52% on the New York Stock Exchange on July 2, closing at $423.06. Trading volume totaled roughly 1.19 million shares, and its market capitalization stood at about $60 billion—approximately ₩93 trillion—erasing some $4.7 billion, or around ₩7 trillion, in a single day.

After completing a $2.875 billion issuance of zero-coupon convertible notes due 2031 on June 11, Ciena has faced renewed concerns over leverage and equity dilution. Those worries, combined with a broader downturn in telecommunications and optical-equipment stocks, have driven its share price lower in recent days. On June 22, the company announced key executive hires aimed at meeting growing AI-network demand, but those moves have so far failed to stem the short-term slide in its stock.

Headquartered in Maryland, Ciena provides high-bandwidth optical transport equipment and software to telecom carriers and hyperscale cloud providers. Fueled by rising AI traffic, it has raised its guidance to project roughly 30% year-over-year revenue growth for fiscal 2026, positioning it as a leading AI-infrastructure beneficiary. However, elevated valuation multiples and the sizeable convertible-note offering have added volatility to the stock.